Even though development of Symbian has all but been abandoned, the open source code still remains in public domain.
Stephane Lenclud has posted the following to the largely abandoned mailing list of the Symbian DevCo:
As Symbian based devices have more or less disappeared from the shelfs and Nokia’s stocks in free fall this mailing list is obviously gone really quiet.
I’m still working with Symbian C++ though. I’ve eventually managed to get around publishing my Symbian branch using CMake as a build system.
Get the source code form the following Mercurial repository: http://hg.slions.net/hgweb.cgi/symbian/
If you are interested in helping out just get in touch.
As of this writing, not much more is known – stay tuned for further info as we get it!